Shock-resistant polystyrene composi-tions containing two rubbery polymers



United States Patent 3 230,186 SHOCK-RESISTANT POLYSTYRIEZNE COMPQSI- TIONS CONTAINING TWO RUBBERY POLYMERS Kurt Kreibich and Karl-Otto Hegel, Marl Kreis Reckling- 3,230,186 Patented Jan. 18, 1966 hausen, Germany, assignors to Chemische Werke E1115 5 h transition metals of g IV to VIII the Aktiengesellschaft, Kreis Recklinghausen, Germany, a Home systemafef a p Vahadlum corporation of Germany ides with aluminum trnsobutyl. N g- Filed 1962, Sell 34 As polydiolefines or diolefine-containing elastomers Ciaims Priority, application y, 1961, are used polybutadiene or polyisoprene, also copolymers i of butadiene and vinyl aromatic compounds, such as sty- 1 Claim (CL 269-4) 10 rene or unsaturated esters, such as fumaric acid ester, It is known that both natural and Synthetic fubbgrs acrylic acid ester, methacrylic acid ester, itaconic acid for example, copolymers of diolefines like butadiene and ester, E1130 natural Iubbeh but Pameulafly p y of vinyl-aromatic compounds like styrene can be added to 20 10 8O ee butadlehe e 80 20 Parts y polystyrene or styrene-containing copolymers. In this The COITIPOSIUOH 0f the mlxmres 15 Preferably 80 e- Way tough thermoplasts which decrease in brittleness leeted F the Percentage of l'llhhehhke polyolefine 1S and sensitivity against sudden mechanical stress with agproxlmately equal to h content of d'lolefihe h the total increasing rubber content are obtained. But on the other e- But the notch Impact l can hhproved hand, the resistance of these products to aging decreases by addlng Small ameuhts 0f the dlolefine-eohtalhlhg with increasing rubber content, since rubber, due to its Peneht, f eXample content of double bonds, becomes brittle under the in- The mlxmres e be p h Oh F0115 1h khefiflers finance of atmcsphel-ic Oxygen and light, particularly at or extruders. It is also possible to dissolve the additions elevated temperatures. It is also known that polyole- 111 Styrene-311d Polymerlle this Plastlclzters fines, like polyethylene, polypropylene, polybutyiene and can also be added to the shock-resistant mixtures to 1mcopolymers of ethylene and propylene can be added to Prove workablllty, as h as plgmehts and hhers polystyrene. These polymers contain no hydrocarbonand the wn i lllaers aga nshaging. double bonds and are therefore not susceptible to aging Ah advantage of thls combination 1S Particularly the like rubber, but the notched-bar impact resistance and low content u le onds and thus a low tendency the impact strength of polystyrene are only improved to to hecome brittle due f g g. I I knOWn that shocka minor extent by these additions. Due to the insufiicient relstaht polystyl'hhes Wlth a l rubheh content become compatibility of these polymers with polystyrene, molded hnthe under h mhhehce of hght F to such an objects of these mixtures have a leafy-fibrous structure, tent that the Impact and notch Impact Strength drops which can be recognized particularly at fractured surhelow that of hhnhal Polystyrene Another advantage facw 1s the improved impact strength at low temperatures of It has been found that age-resistant and impact-resist- 0 9 Compared to shock'reslstaht Polystyrehes ant polystyrene and styrene containing copolymers can which cohtalh only rubberbe produced with advantage by adding a combination EXAMPLE1 of from 0.1 to 20 parts of an amorphous, rubber-like polyolefine and from 1 to 40 parts of a polydiolefine or (a) On a two roll-mixing mill 75 to 98 parts polydiolefine-containing elastorner to from 99 to 66 parts styrene containing 2% butyl sterate, 0 to 15 parts of a polystyrene and styrene-containing copolymers. The copolymer of 40 parts butadiene and 60 parts styrene molded objects produced therefrom show no leafy strucand 0 to 25 parts of a copolymer of 57 parts ethylene ture, because the diolefine-containing elastomer produces and 43 parts propylene, whose reduced specific viscosity a better compatibility of the components. 45 in p-xylene is 2.5 are mixed for 10 minutes at 135 C. The process is suitable for the production of shock- The resulting homogenous mixture is ground and injecproof polystyrene and copolymers of styrene with for tion molded to standard testing rods.

Table I a I Copolymer of 40 Ocpolyrner of 57 i Polystyrene parts butadiene parts ethylene Impact Notch (parts by weight) and 60 parts and 43 parts strength impact styrene (parts propylene (kgjcmjcmfl) strength by weight) (parts by weight) (kg/cmJcmfi) l 1 as I 15 0 5.0 as t 15 2 so 6.2 81 15 4 so 6.2 79 15 6 87 10.5 77 15 s 81 8.1 as 0 2 24 1.9 96 0 4 32 1.9 94 0 s 32 1.9 s5 0 15 1a 1.9 i 0 25 Can not be injection molded example, monomers like alpha-methylstyrene, nuclearmethylated styrenes and esters of acrylicand methacrylic acids, itaconic acid, fumaric acid, maleic acid, acrylnitrile or vinyl acetate.

Suitable amorphous, rubber-like polyolefines are atactic polypropylene, polybutylene and their copolymers, also copolymers of these olefines or olefine mixtures with ethylene, particularly copolymers of ethylene and (b) On a two roll-mixing mill are produced a mixture I of 71 parts polystyrene, 28 parts of a copolymer of 40 parts butadiene and 60 parts styrene and 1 part butyl stearate and a mixture II in which only 24 parts of the butadiene copolymer are used with four parts of ethylene-propylene copolymer, the other components being the same as in mixture I. The rolling and testing was eifected as in Example 10.

3 4 Table 1b ganic phase 2:1) with 0.6% polyvinyl alcohol as a suspension stabilizer with stirring for three hours at 110 C, I t t th h, 3 hours at 130 C., and 3 hours at 140 C., whereby a figjg if fi t j gggfj fjfg granular polymer (a) is obtained. The latter is com- 5 pressed on a rolling mill, ground and injection molded to At 0 M At 0 At standard testing rods. The measured values compiled in Table 3 show the improvements compared to a polymer MixtureI 84 136 L7 Without addition of the butadiene-styrene copolymer (c) Mixture II 84 and a polymer Without addition of the copolymer of ethylene and propylene (d).

Table 3 Copolymer of Copolymer of Polystyrene 24 parts buta- 43 parts ethylene Impact Notch impact (parts by weight) diene 76 parts of 57 parts prostrength strength styrene (parts pylene (parts (kg/ernJcmfl) (kg./cm./cm.

by welght) by welght) (a) 2. 9 5 65.1 4.0 (b) 4.3 1 50.0 8.1 (c) 7 15.0 2.4 (d) 4.3 34.4 2.5

As appears the values for impact strength and notch EXAMPLE 4 impact strength are greatly improved, even at low temperatures.

(c) As described under 1a, the mixtures listed in Table 10 were rolled for 20 minutes at 135 C. and tested.

A solution of 3.5 parts by weight of a copolymer of 76% butadiene and 24% styrene, pants by weight acrylonitrile and 1 part by weight of an ethylene/propylene copolymer in 59.5 parts by Weight styrene is mixed with 2 30 parts by weight ethyl acrylate, 4 parts by weight stearic Table 16 Oopoly-mer of Atactic Polystyrene parts but-adiene polypropylene Butylstearate Impact strength Notch impact (parts by and parts (parts by (parts by (kg./cm./cm. strength Weight) styrene (parts weight) weight) (kgJcmJcmJ) by weight) EXAMPLE 2 acid butyl ester and 0.16 part by weight ditertiary butyl In the same manner were produced mixtures of 0 to 24 parts of a copolymer of 25 parts by weight butadiene and 75 parts by weigh-t dibutyl fumarate, 70 to 96 parts polystyrene containing 2% butyl stearate, and 0 to 6 parts of a copolymer of 50 parts ethylene and 50 parts propylene, and tested as above.

peroxide, and polymerized as described in Example 3. The polymer after Working up has an impact strength of 44 kg. cm./cm. a notch impact strength of 6.9 kg. cm./cm. and a bending strength of 988 kg./cm.

In all instances in the foregoing description, in the absence of any other indication, the word parts means parts by weight.

A solution of 5 parts by weight of a copolymer of 43 parts ethylene and 57 parts propylene and 2.9 parts by weight of a butadiene/styrene-copolymer, commercially available under the name Plioflex 1006, in 86 parts by weight styrene is heated, after addition of 2 parts by weight ethyl acryllate, 4 parts by weight stearic acid butyl ester and 0.16 parts by Weight ditertiary butyl peroxide, as a catalyst, in an aqueous suspension (phase ratio waterzor- A shock resistant composition comprising, on the basis of parts by Weight of the Whole composition, from 99 to 66 parts by Weight of a material selected from the group consisting of polystyrene and copolymers of styrene with alpha-methylstyrene, nuclear-methylated styrenes, acrylonitrile, vinyl acetate, acrylic acid ester, methacrylic acid ester, itaconic acid ester, fumaric acid ester and maleic acid ester, from 0.1 to 20 parts by Weight of an amorphous, rubber-like polyolefine selected from the group consisting of polypropylene, polybutylene, copolymers of propylene and butylene With each other and copolymers of propylene and butylene and mixtures thereof with ethylene and 1 to 40 parts by weight of an elastorner selected from the group consisting of natural rubber, polybutadiene, polyisoprene and copolymers of butadiene with styrene, furnaric acid ester, acrylic acid ester, rnethacrylic acid ester and itaconic acid ester.

References Cited by the Examiner UNITED STATES PATENTS 6 2,808,386 10/1957 DAlelio 260892 2,834,750 5/1958 Salyer et al. 260-880 3,014,8871 12/1961 Haward 260-888 FOREIGN PATENTS 861,542 2/1961 Great Britain,

OTHER REFERENCES Natta et al.: Rubber and Plastics Age, vol. 42, pages 10 53-58, January 1961. (Copy in Scientific Library.)

MURRAY TILLMAN, Primary Examiner.

LEON I. BERCOVITZ, Examiner. 

